Sony SEQ-555ES - Notes on Repair

SEQ-555ES
General
Power
requirement
120
or
240
V
ac,
adjustable,
50/60
Hz
(AEP,
E
model)
120 V ac, 60 Hz (US, Canadian model)
Power consumption 25 watts
AC outlets (US, Canadian only)
2 switched, 450 watts max.
1 unswitched, 450 watts max.
Dimensions
Approx.
430
x
105
x
275
mm
(wi/h/d)
(17
x
4Y,
x
107,
inches)
including projecting parts and
controls
Weight Approx. 5.2kg (11 1b 802)
Approx. 6.5kg (141b 502) in shipping
carton
FEATURES
The SEQ-555ES program equalizer is a system control
center that provides you with maximum enjoyment from
the world of audio-video presented by digital audio
sources such as CD (Compact Disc) and PCM (Pulse
Code Modulation), and by Hi-fi video. It also works as an
ordinary graphic equalizer, allowing you to create your
own original sound.
System selector for the AV era
Enriched input/output terminals, in line with the develop-
ment of systems connected with AV (Audio-Video)
units *, characterized by clear image and excellent tone
quality, especially with a Hi-fi video unit connected.
Five input and three output channels, permitting signal
switching with the SEQ-555ES main unit or with the sup-
plied remote commander RM-31, are provided.
* As no video signal terminal is provided in the SEQ-555ES, it is not
possible to process the video signal.
Automatic equalization
The flat frequency response of the playback, including
the listening room and speaker, gives a reference for op-
timizing adjustment of each frequency band with the
equalizer.
In the SEQ-555ES, the sound field is measured and
analyzed by the built-in microprocessor combined with
the microphone, supplied especially for sound field
measurement. Adjustment inverse to the analysis result
is automatically carried out so that the frequency
response becomes flat at the measuring position.
Infrared remote commander
Each time adjustment is made by operating the equal-
izer switches and controls, the effect at the listening
position must be checked with the conventional graphic
equalizer.
However, ideally, adjustment should be carried out with
the listener actually at the listening position.
The RM-31 remote commander makes this possible. In
addition to on-band equalizer adjustment, it permits
on/off control of the power supply (US, Canadian), input
selection recall of memorized equalizer curves and sound
volume control.
Memory permitting immediate recall of equalization
As it is difficult to determine the most appropriate levels
of equalizer adjustment, four equalization curves of dif-
ferent types of music are stored in the fixed memory of
the SEQ-555ES. Each curve can be recalled by one-touch
operation of the corresponding key. Moreover, four
memories are provided for storing original curves made
by the user.
NOTES ON REPAIR
The frequency response of this set is adjusted to
match the microphone. Therefore, frequency re-
sponse adjustment is required when the microphone
is replaced. (Refer to page 23, Frequency Response
Adjustment.)
REPAIR CHECK POINTS
1. Before checking the microcomputers, be sure
that power supply voltage is being properly
applied and that the clock signal is being applied.
Also confirm that the reset pin is high.
Microcomputers A (IC751) and C (IC451) are
controlled by microcomputer B (1C501).
. Microcomputer A (IC751)
This microcomputer controls key input and re-
mote control input. It sends the data to micro-
computer B when there is key input or remote
control input.
Checking is performed as follows.
@ Data should be output at pin ay when the
power supply plug is pulled and then plugged
in again.
@ Pin (5) and (16) interrupt signals should be
generated when any key is pressed.
@ A microcomputer clock signal (4.19MHz)
should be being applied to pin(7).
® Confirm that pins Q) — key scan signals
are being output’ (except for pins and @5)
@ Pin should be high level. When this pin is
low, the key scan signal is not output and key
input is not accepted.
@ Pins Q) _ (4) are for accepting key input, so
check that the key scan signal of any pin
appears when a key is pressed.
bo
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